Improvement in compound engines



ivITED STATES PATENT OFFICE.

WTILLIAM BAXTER, JR., OF NEWARK, NEW JERSEY.

IMPROVEMENT IN COMPOUND ENGINES.

Specification forming part of Letters Patent No. 153,300, dated .Tnly 21, 1874; application filed February 18, 1874.

To cli whom it may concern:

Be it known that I, WILLIAM BAXTER, J r., of the city of Newark, in the county of Essex and State of New Jersey, have invented certain Improvements in Compound Engines, of which the following is a specilication:

This invention relates to engines in which the steam, after it has performed its duty in one or more cylinders, is exhausted into a cylinder of larger capacity, where it continues its duty, subject to expansion, and may be ultimately passed to a condenser, to give the piston oi' the larger cylinder the advantage of a vacuum.

The improvements are fully hereinafter described and claimed.

In the accompanying drawing, Figures 1 and 2 represent, mainly, central vertical sections, in planes at right angles to each other, of a compound engine constructed in accordance with the invention. Fig. 3 is a horizontal section upon a larger scale, mainly as indicated by the line .r of the cylinders, valvechest, and certain of the passages.

Similar letters of reference indicate corresponding parts.

In the particular application of the invention shown in the drawings, the engine-cylinders are represented as occupying an overhead position; but this may be reversed, or, instead ot the engine being vertical, it may occupy a horizontal or inclined position.

A Al are the two high-pressure cylinders disposed one on either side of the low-pressure cylinder B, all of which may be steamjacketed. C C and D are the pistons ot' said cylinders. The pistons C C of the smaller and outside or high-pressure cylinders A Al are connected by their rods a a with the ends ot' a sliding cross-head, E, which works up and down within guides F F on opposite sides of the mainframe. The piston D of the intermediate and larger or low-pressure cylinder B is connected, by its rod b, with the same crosshead E at its center.

inasmuch as the cylinders A A are of the saine diameter, and their pistons exposed to equal pressures, there is no tendency oi' the cross-head to tip or tilt at its ends, and it is stii'ened or steadied at its center by the connection therewith of the intermediate or larger piston D. This gives a very firm and effective action, and divides the strain over the crosshead.

Rotary motion is communicated to the engine-shaft G from the cross-head E by pitman H and wrist-pin d. lVhile the pistons of the three cylinders A A B are each made to communicate their respective forces to the crosshead E, the power exerted by the pistonsCG is more directly applied, as it were, to working the feed-pump I and air-pump J of the engine by the extension of the piston-rods a a below or beyond the cross-head. This, too, forms a very compact, simple, and ei'ective combination. K is the valve-chest, which is common to all the cylinders, and contains a single valve, which may either be a straight sliding valve, or a curvilinearly-vibrating one, but which is constructed substantially as follows, to control the admission and delivery to and from all the cylinders. Thus, said valve L is ot' a double-D shape-that is, one D outside ofthe other; or, in other words, is formed with an inner-face cavity, e, and an outer passage,f, which latter also opens at its ends in or through the face of the valve. Such valve is of a width and length to control the following ports and passages, viz: Ports and passages g g leading from the valve seat or face to the upper ends of the cylinders A A; similar ports or passages g g leading to the lower ends of said cylinders', also, a central exhaustport, h, which may lead to the condenser; and ports and passages fi t" connecting the valvechest or valve-seat with the upper and lower ends oi' the low-pressure cylinder B. When the valve is shifted to allow steam from the valve-chest to pass either one end ofthe valve and enter, by the one set of passages, g gor g gf, the upper or lower ends of the cylinders A A', such motion brings the outer passage f in the valve in communication with the other set of said passages g g or y g', and passes the spent steam in the cylinders A A from the opposite sides of the pistons therein, by one ot' the passagesi or if, to the cylinder B, while the other of said passages e' or e" is put in communication, by the cavity e and exhaust-passage h, with the condenser, or with the atmosph ere, the exhaust steam from the cylinders A Al acting simultaneously on the piston D with the live steam from the valve-chest on the pistons O C', and the pressure being on correspending faces of all the pistons to reciprocate them in common.

The requisite motion maybe communicated to the Valve L by an eccentric, l, ou the main shaft, made to rock a shaft, m, which in its turn, by crank or arms and connecting-rod, rocks a way-shaft, n, that, by a further crank or arm, o, and rod 1', reciprocates the valve, as required. Furthermore, the rod connecting the rock-shaft n with the rocl-sl1aft m may be connected with the latter by a reversing-slide similar in its action to the link motion in other 

